The National Institute on Drug Abuse (NIDA), Medications Development Division (MDD) has established a Cocaine Treatment Discovery Program (CTDP) to identify potential treatments for the medical management of cocaine dependence. This program involves testing compounds through a decision-based screening scheme which consists of a number of in vitro and in vivo assays and which is designed to identify potential treatment agents which either substitute for cocaine or antagonize the effects of cocaine. The purpose of this contract is to preclinically evaluate the effects of 100 test compounds on the subjective effects of cocaine; as assessed by the rat drug discrimination procedure. Depending upon results obtained from the locomotor activity test, which is conducted under a separate contract, the test compound will be evaluated for the ability to substitute for, or antagonize, the discriminative effects of cocaine. The compounds to be tested under this contract will be selected and, for the most part, supplied by NIDA. Compounds will be supplied under an identification code number with appropriate information including physical properties, solubilities, and recommended starting doses, if available. CTDP data generated from this contract on proprietary compounds will be maintained in confidence by NIDA unless permission to release the data is granted to NIDA by the compound submitter. Compound submitters are free to disclose CTDP data generated on their compounds at any time.